In general, there are two types of methods for manufacturing a steel tube: an injection method and a method by using a steel plate. Since the injection method increases the cost of manufacture, many choose to process a steel plate into a tube.
Particularly, a steel tube obtained through the latter method is called an electric weld tube since a steel plate is transformed to a tube and its contacts are welded through electric resistance welding.
In effect, the method used for manufacturing such electric weld tube is now used in a wide range of applications in both large bore steel tubes and small bore steel tubes. Especially, small bore steel tubes are broadly used as a condenser for cooler equipment such as refrigerators or a hydraulic brake line, in which high durability and high reliability are required. Therefore, the small bore steel tube must be carefully managed from its manufacturing process.
In this same context, studies on more effective surface treatment techniques are in progress to prevent the corrosion on the surface of a small bore steel tube.